/**
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.waveprotocol.wave.model.operation.wave;

import org.waveprotocol.wave.model.operation.OperationException;
import org.waveprotocol.wave.model.wave.ParticipantId;
import org.waveprotocol.wave.model.wave.data.WaveletData;

/**
 * Operation class for the remove-participant operation.
 */
public final class RemoveParticipant extends WaveletOperation {
  /** Participant to remove. */
  private final ParticipantId participant;

  /**
   * Creates an remove-participant operation.
   *
   * @param participant  participant to remove
   */
  public RemoveParticipant(ParticipantId participant) {
    if (participant == null) {
      throw new NullPointerException("Null participant ID");
    }
    this.participant = participant;
  }

  /**
   * Gets the participant to remove.
   *
   * @return the participant to remove.
   */
  public ParticipantId getParticipantId() {
    return participant;
  }

  /**
   * Removes a participant from the given wavelet.
   */
  @Override
  public void doApply(WaveletData target) throws OperationException {
    if (!target.removeParticipant(participant)) {
      throw new OperationException("Attempt to delete non-existent participant.");
    }
  }

  @Override
  public WaveletOperation getInverse() {
    return new AddParticipant(participant);
  }


  @Override
  public String toString() {
    return "RemoveParticipant(" + participant + ")";
  }

}
